Molecule opacities of X<sup>2</sup>Σ<sup>+</sup>, A<sup>2</sup>Π, and B<sup>2</sup>Σ<sup>+</sup> states of CO<sup>+</sup>

Carbon monoxide cation (CO⁺) plays a dominant role in some astrophysical atmosphere environments, where theoretical studies of its opacity are essential for radiative transport modeling. In this work, based on experimentally observed vibrational energy levels of the X²Σ⁺, A²Π, and B²Σ⁺ electronic states of CO⁺, we refined and constructed potential energy curves using a Modified Morse (MMorse) potential function, then the vibrational energy levels and spectroscopic constants are extracted. In the meantime, the internally contracted multireference configuration interaction approach (MRCI) with Davison size-extensivity correction (+Q) is employed to calculate the potential energy curves and transition dipole moments. The refined MMorse potential exhibits excellent agreement with the computed potential energy curves, while the spectroscopic constants and vibrational levels show strong consistency with existing theoretical and experimental data. The opacities of the CO⁺ molecule is computed at different temperatures under the pressure of 100 atm. It is found that with the increase of temperature, the opacities for transitions at long wavelength range are enlarged because of the larger population on excited electronic states at the higher temperature.